[nws-changes] 20090503: criterion for hail size

• To: nws-changes@xxxxxxxxxxxxxxxx
• Subject: [nws-changes] 20090503: criterion for hail size
• From: Linda Miller <lmiller@xxxxxxxxxxxxxxxx>
• Date: Mon, 04 May 2009 13:56:56 -0600

NOUS 41 KWBC 041632
PNSWSH

SERVICE CHANGE NOTICE 09-36
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
330 PM EDT MON MAY 4 2009

TO:      SUBSCRIBERS:
        -FAMILY OF SERVICES
        -NOAA WEATHER WIRE SERVICE
        -EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
        OTHER NWS PARTNERS...AND NWS EMPLOYEES

FROM:    CRAIG SCHMIDT
        CHIEF...METEOROLOGICAL SERVICES DIVISION
        WESTERN REGION HEADQUARTERS SALT LAKE CITY UT

SUBJECT: EXPERIMENTAL CRITERION CHANGE FOR HAIL SIZE IN SEVERE
        THUNDERSTORM WARNING DETERMINATION AT ALL WESTERN
        REGION WEATHER FORECAST OFFICES FROM THREE-QUARTER
        /0.75/ INCH TO ONE /1/ INCH IN DIAMETER OR LARGER
        EFFECTIVE JUNE 1 2009

ON JUNE 1 2009...ALL WESTERN REGION /WR/ WEATHER FORECAST
OFFICES /WFOS/ WILL BEGIN USING A NEW EXPERIMENTAL HAIL
CRITERION FOR DETERMINING WHEN TO ISSUE SEVERE THUNDERSTORM
WARNINGS /SVR/.  IN AN EFFORT TO BETTER REPRESENT HAIL WHICH
PRODUCES DAMAGE AND TO REDUCE USER COMPLACENCY TO NUMEROUS
SEVERE THUNDERSTORM WARNINGS FOR THREE-QUARTER /0.75/ INCH
DIAMETER HAIL...THE WFOS IN WR WILL USE HAIL CRITERION OF ONE
/1/ INCH IN DIAMETER OR LARGER AS OPPOSED TO THE REFERENCED
/0.75/ INCH CRITERION.  THERE IS NO CHANGE IN HAIL CRITERION FOR
AVIATION THUNDERSTORM WARNINGS /I.E. CONVECTIVE SIGMETS/ OR FOR
SPECIAL MARINE WARNINGS /SMW/.

A SERVICE CHANGE NOTICE /SCN/ ANNOUNCING THE NWS CENTRAL
REGION/S /CR/ SIMILAR EXPERIMENT IS AVAILABLE ONLINE AT /USE
LOWER CASE LETTERS/:

    HTTP://WWW.WEATHER.GOV/OS/NOTIFICATION/SCN09-19HAIL_CHANGE.TXT

A PRODUCT DESCRIPTION DOCUMENT /PDD/ FOR THIS WR EXPERIMENT IS
AVAILABLE ONLINE AT /USE LOWER CASE LETTERS/:

    HTTP://PRODUCTS.WEATHER.GOV/

THIS EXPERIMENT WILL BE IMPLEMENTED FOR ALL AREAS IN EIGHT
WESTERN STATES: ARIZONA...CALIFORNIA...IDAHO...MONTANA...
NEVADA...OREGON...UTAH AND WASHINGTON.

NO CHANGE WILL OCCUR WITH RESPECT TO WIND SPEED IN SEVERE
THUNDERSTORM WARNINGS. WINDS EQUAL TO OR IN EXCESS OF 50 KNOTS

FOR THUNDERSTORMS EXPECTED TO PRODUCE AROUND 3/4 INCH TO 7/8
INCH DIAMETER HAIL BUT REMAIN BELOW SEVERE WIND LIMITS...WR WFOS
ARE EXPECTED TO USE THE SPECIAL WEATHER STATEMENT /SPS/...
HEADLINED AS A SIGNIFICANT WEATHER ADVISORY.  WFOS WILL ALSO
CONTINUE TO COLLECT AND DISTRIBUTE HAIL REPORTS THAT ARE THREE-
QUARTERS /0.75/ INCH IN DIAMETER OR GREATER BY WAY OF THE LOCAL
STORM REPORT /LSR/ AS USUAL.

IF YOU HAVE QUESTIONS...PLEASE CONTACT:

   CRAIG SCHMIDT
   NATIONAL WEATHER SERVICE
   WESTERN REGION HEADQUARTERS
   125 SOUTH STATE STREET
   ROOM 1311
   SALT LAKE CITY UT 84138
   801-524-4000
   CRAIG.SCHMIDT@xxxxxxxx

NATIONAL SERVICE CHANGE NOTICES ARE ONLINE AT /USE LOWER CASE LETTERS/:

    HTTP://WWW.WEATHER.GOV/OM/NOTIF.HTM

$$
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